1. Field of the Invention
The invention relates to a developing apparatus mounted on an image forming apparatus such as a copier or a printer, and particularly to a developing apparatus having a spacer for keeping a developing roller at a predetermined interval relative to an image bearing member such as a photosensitive member.
2. Description of Related Art
For example, in an image forming apparatus using the electrophotographic process, when the use thereof reaches a long time, the interchange of a photosensitive drum, the supply or interchange of a developer and the adjustment, cleaning and interchange of others (such as a charger and a cleaning container) become necessary, but such maintenance work has been virtually difficult to other persons than a serviceman having expert knowledge.
So, in an image forming apparatus using an image forming process of the electrophotographic type, there is adopted a process cartridge system in which a photosensitive drum and process means for acting on the photosensitive drum are integrally made into a cartridge which is detachably mountable on the image forming apparatus. According to the process cartridge system, the maintenance of the apparatus can be done by a user himself without resort to a serviceman and therefore, the operability of the apparatus can be markedly improved.
FIG. 16 of the accompanying drawings is a schematic cross-sectional view showing a process cartridge according to the conventional art.
The process cartridge B is comprised of a developing unit 12 comprising a developing apparatus 9 having a developing roller 9c, a regulating blade 9d, etc., and a toner frame 11 having a toner container 11A, the developing apparatus 9 and the toner frame 11 being joined together by welding, and a cleaning frame 13 supporting a cleaning container 10 having a photosensitive drum 7, a charging roller 8 and a cleaning blade 10a. The developing unit 12 is pivotally supported by a coupling pin 22, and the developing roller 9c is biased toward the photosensitive drum 7 side by a compression coil spring 22a. 
In this case, in order that the photosensitive drum 7 and the developing roller 9c may maintain an appropriate gap therebetween, spacer runners 9i are provided at the lengthwisely opposite ends of the developing roller 9c, and the appropriate gap between the developing roller 9c and the photosensitive drum 7 is maintained by the abutted position of the spacer runners 9i and the photosensitive drum 7.
Now, when effecting image formation with the above-described process cartridge B according to the conventional art mounted on an image forming apparatus, a small amount of toner is scattered outwardly from around the developing roller 9c during the development by the developing roller 9c of the developing apparatus 9.
If the scattered toner adheres to the peripheral surfaces of the spacer runners 9i provided at the lengthwisely opposite ends of the developing roller 9c, the appropriate gap between the developing roller 9c and the photosensitive drum 7 becomes unmaintainable and bad development occurs, and this has led to the problem that good images become unobtainable for a long period.
The present invention has been made in view of the above-noted problem and an object thereof is to provide a developing apparatus in which the gap between an image bearing member and a developing roller can be accurately maintained for a long period.
Another object of the present invention is to provide a developing apparatus in which a spacer for determining the gap between an image bearing member and a developing roller can be cleaned by a simple method.
Still another object of the present invention is to provide a developing apparatus in which electrical leak can be prevented and yet the cleaning of a spacer can be effected.
Yet still another object of the present invention to provide a developing apparatus comprising:
a developer bearing member for bearing and conveying a developer thereon, the developer bearing member having at a lengthwise end portion thereof a spacer for keeping a spacing between the developer bearing member and an image bearing member;
a sealing member for preventing the leakage of the developer from the lengthwise end portion of the developer bearing member;
a conductive member disposed in the vicinity of the sealing member; and
an insulation member provided between the sealing member and the conductive member for electrically insulating the sealing member from the conductive member,
the insulation member having a cleaning portion for cleaning the spacer.
Further objects of the present invention will become apparent from the following detailed description when read with reference to the accompanying drawings.